hash.js•1.1 kB
import * as crypto from 'node:crypto';
const hashes = Object.create(null);
//TODO shorter?
const hash_length = 12;
/**
* replaces +/= in base64 output so they don't interfere
*
* @param {string} input
* @returns {string} base64 hash safe to use in any context
*/
export function safeBase64Hash(input) {
if (hashes[input]) {
return hashes[input];
}
//TODO if performance really matters, use a faster one like xx-hash etc.
// should be evenly distributed because short input length and similarities in paths could cause collisions otherwise
// OR DON'T USE A HASH AT ALL, what about a simple counter?
const md5 = crypto.createHash('md5');
md5.update(input);
const hash = toSafe(md5.digest('base64')).slice(0, hash_length);
hashes[input] = hash;
return hash;
}
/** @type {Record<string, string>} */
const replacements = {
'+': '-',
'/': '_',
'=': ''
};
const replaceRE = new RegExp(`[${Object.keys(replacements).join('')}]`, 'g');
/**
* @param {string} base64
* @returns {string}
*/
function toSafe(base64) {
return base64.replace(replaceRE, (x) => replacements[x]);
}